Triangle end cap needs clamp...

[556ready]

I put a low pro gas block on my mid length set up and got MOE rifle length hand guards (just wanted to change up the look of the rifle). I put the triangle end cap on the front to hold everything in place. I now need a clamp or something other behind it, to hold end cap in place. Suggestions?

 

[Numidian]

Do you have a front sight base? You can just tap the gas tube hole in the FSB and then run a bolt through the cap into the FSB